This invention relates to a surface rewinder and method and, more particularly to a rewinder wherein the operation of one of the winding rolls features a unique speed profile.
In the past, two basic types of surface rewinders have been available commercially. One type of surface rewinder is seen in co-owned U.S. Pat. No. 4,909,452 and features a movable winding drum. More particularly, the transition of the core and partially wound product from one side of the nip of the winding drums to the other is done with a combination of lower drum movement, infeed transfer finger exposure and speed differential between the two drums. At the beginning of the cycle the distance between the two winding drums is very quickly dropped. The infeed transfer fingers are then proportionately exposed and this, along with a small speed differential between the drums, drives the product from one side of the drums' nip to the other. This allows the diameter of the product to build and move through the transition from one side to the other without additional compression.
Another surface rewinder can be seen in U.S. Pat. No. 4,327,877. This uses a speed change of one of the rolls to quickly move the core and product partly wound thereon from one side of the pair of winding rolls to the other. This method compresses the product while the speed change advances the product. In operation, the lower drum speed quickly slows by controlled deceleration and then returns to and maintains a constant speed differential through the remainder of the wind cycle.
In each case, there is a degree of dependency on slippage between the product and the surfaces in contact therewith. If the drum surfaces are smooth enough to allow slippage, they also permit unstable products (typically soft rolls) which easily bounce around in the three drum winding area limiting the speed at which they can be run.
According to the invention, the three drum cradle includes spaced apart first and second winding drums with control means operably associated with the drums for changing the rotational speed of one drum to substantially eliminate slippage and also provide a speed profile in this drum wherein the speed of the drum is decreased in the beginning of each winding cycle to advance a partially wound roll through the space between winding drums and thereafter increasing the speed of the specific drum as a function of the increasing diameter of the partially wound roll. Other objects and advantages of the invention may be seen in the details of construction and operation set forth in the ensuing specification.